In the field of wireless communication systems, multicarrier communication has recently attained increasing interest and consideration.
In the context of a 3GPP system environment, various HSDPA techniques are developed for supporting multicarrier operations.
In HSDPA using a single carrier (typically having 5 MHz bandwidth), a receiver with 5 MHz bandwidth is typically used to receive the single HSDPA carrier.
In 3GPP release 8, DC-HSDPA is specified, wherein a terminal is able to receive and to be scheduled on two adjacent 5 MHz HSDPA carriers. The typical RF architecture to receive this type of signal has 10 MHz bandwidth, and also typically direct conversion receivers with a single mixing stage, i.e. contiguous-bandwidth low-complexity receivers, are used for mobile devices. When such receivers are employed for DC-HSDPA, 10 MHz bandwidth is used for covering the two adjacent 5 MHz HSDPA carriers, with the local oscillator tuned between the two carriers of interest.
In 3GPP release 9, multicarrier HSDPA is extended such that the two adjacent HSDPA carriers can reside on different bands, which is referred to as DB-DC-HSDPA.
In 3GPP release 10, the approach is further extended to a total of four HSDPA carriers, which is referred to as 4C-HSDPA, while in 3GPP release 11, 8C-HSDPA with a total of eight HSDPA carriers, is considered. In both 4C-HDSPA and 8C-HSDPA, the carriers are arranged such that those carriers residing on the same band need to be adjacent. Accordingly, in these techniques, a mixture of adjacent carriers from the same band, and carriers from different bands can be received (e.g., in the case of 4C-HSDPA, 2+2 meaning 2 adjacent carriers from 2 different bands, respectively).
In the context of a LTE system environment, various carrier aggregation (CA) techniques are developed for supporting multicarrier operations. Specifically, contiguous intraband carrier aggregation (CA) for both downlink and uplink is considered in this regard.
Accordingly, any one of the above-mentioned conventional techniques for multicarrier communication, including HSDPA and contiguous intraband CA, require that the multiple carriers to be received on the same band are adjacent to each other. Thereby, a contiguous spectrum range is provided, which is easy to properly receive for the typically deployed contiguous-bandwidth low-complexity (direct conversion) receivers with an appropriate bandwidth to receive the contiguous spectrum range.
However, the conventional assumption of adjacent carriers to be received on the same band is obsolete in certain modern and future wireless communication systems. This is essentially due to non-adjacent spectrum allocations to different operators, e.g. in Europe and the US. As a result, there is an increasingly strong interest in performing multicarrier communication, including HSDPA and (E-UTRA) CA, with non-adjacent carriers, i.e. in a non-contiguous spectrum range, in the same band.
Receiving such non-adjacent carriers, i.e. non-contiguous spectrum range, in the same band is specifically problematic with the typically deployed contiguous-bandwidth low-complexity (direct conversion) receivers. Yet, the use of such receivers is desirable in terms of complexity and cost considerations which are specifically relevant for mobile devices.
Thus, there is a need to further improve such multicarrier systems, i.e. multicarrier communication support, especially in terms of non-adjacent multicarrier support for a contiguous-bandwidth receiver.